Superheater boiler



July 5, 1932- w. H. ARMAcosT 1,866,387

SUPERHEATER BOILER Filed March 2s, 1329 2 sheets-sheet 1 ATTORNEY E July 5, 1932- w. H. ARMAcosT SUPERHEATER BOILER Filed March 28. 1929 2 Sheets-Sheet BY* @fw ATTORNEY Patented July 5, 1932 Winnen n. Anamnese, or 'inw' Yoeri, n. Y Ass'ena fro snrn'artnnrnn 00M- PANY, or Yoan, Y. f

'snrnn'rtnivrnn Boi-EER applicati@ ined YMarch 28, 1929. 'serial fno. A350,566.

My invention 1relates to superheaterboilers and has .particular reference to--large po'vv'er boilers designed to operate'at relatively high P'SSSUGS.

. ain boilers of this general character, the size of the individual elements together with the high saturated steam temperatures encountered result inexpansion andcontraction of parts of the boiler With respect to each other of such magnitude that the satisfactory mounting of such elements has proved to be a very difhcult problem.

y@ne of the principal objectso'f the present invention is lthe provision of a novel boiler construction particularly Withvreference vto the arrangement of boiler Vdrums and superheater headers Which Will provide a deg-ree of flexibility hitherto unobtained and sufficient to tahe'care of the'extreme expansions and contractions encountered inhigh :pr-essure boilers. Numerous other objects and advantages incident to my invention Will be more specifically pointed out -in "the ensuing description of the several embodiments thereof `illustrated in the accompanying dra-Wings forming a part hereof, in which Fig. l is a fragmentary vertical Vsection 'showing fthe upper Iportion yof a s uperheater boiler embodying the invention; Fi-g. 2 is Ya fragmentary section taken alongtheline2f--2 of Fig. l; Fig. 3 is a vertical section illustrating another form of the invention and Fig. i is a vfragmentary section of -a -still further modified form of the invention.

y Referring new to Fig. Lthefboiler chosen for illustrative ypurposes is of fthe double semi-vertical type 'comp-rising l-tyvin steam generating units A and 'B mounted in a cemmen setting. One yofthe units comprises fthe steam and Water drums 1 and-2 connected bythe banks of steamv generating tubes 3, fr and 5 to the usual mud drums (notshown). Water circulators 6 and steam Circulators -7 connect drums l and 2 in the usual manner.

The second steam generating unit is similar in form to the one just described andcomfprises steam and Water drums 8 andf9, banks of generating tubes 1 0, ll and 12,7Water ci'rculators 13 and steam circulators 14.v y

The generating units are tired fromacomf mon furnace 15 and in the form shown the gases from the furnace are directedin three passes over each of thezgenefrating units by means of baflie 16 as indicated bythe arrows on the draWings,to the usualseparate outlet flues lor breechings (not shown) The specie form vand -bafliing arangementv of the boiler is notlge'rrnane to the present inventioma'nd a more detailed description thereof is therefore not deemed 'necessary herein.y

The generating units A and'B aregprovided respectively ywith; elevated steam drums '17 and `18, 4drum li' being connected tojdrum l by a plural-ity ojf r-oWs of 4tubes 119 which, as Will Abe observed from Fig. '-2. are lUniforrnly distributed o'ver substantially y the entire length of the drums.n The number of rows of tubes employed will varyaccording to the capacity and rating for Which the 'boilei` is designed, but it is preferable to provide a sufficient number of tubes so 'that `the steam velocity through tubes 19 =does not exceed a velocity of 100 -feet per second. The reason for this Will appear later. Ai-similar group of tubes 20 serves to connect the drums 9 and 18. V I l.

Drums -17 Aand '18 lmay be provided'with baliies 2l and 22and drainage tubes 23 and 24, the latte-r preferably .being connected respectively *to drumsl and 9. A

Thefdrums 17 'and 18 are connected respectively by rows of tubes .fand 26 -toja header 27 Whi'chr-v'vi-llhereinafter be referred toas an intermediate header. Tubes and 26 are arranged along 1 substantially the' full f lengthy of Adrums 1-7 and 18 yand header 27 lin the manner shownrniore clear-ly in Fig. 2. It is preferred that the total-cross sectionof tubes in` group 19 and the `tubes -in `group 20 be greater-than the total 'cross section of Jthe tubes ingroup `and the tubes in group 26, and for, Athis purpose the tubes in group 19 are made more numerous, asf shown, than those in .grou-p 25,- f and the tubes virl-*group 20 merev vnummreus `than `these of :group 26, the individual tubes beingy assumed' to have the saine cross section-fineach of Vthe separateV groups V Y As shown, the `-superheater lcomprises an inlet header 28 and an outlet header 29'fconnected by a plurality of tubular superheater elements 30 arrange-d in two groups one of which extends into the intertube space of the tube bank 5 and the other of which is similarly positioned in tube bank 12. Elements 30 are preferably so formed that, when in place, the portions passing through the roof of the boiler are vertical and as, in all the forms of the invention illustrated, the lateral thrusts on the superheater headers 28 and 29 are substantially balanced, what residual motion there may be between the superheater headers and the steam and water drums of the boiler units will be almost exactly vertical so that the vertical position of the elements at the points where they penetrate the boiler setting reduces to a minimum the stresses on the joints of the superheater and on the setting. i

The intermediate header 27 is closed at one end and at its other end is connected by means of the pipe 31 to the corresponding lli Gis

end of the superheater inlet header 28. The superheater outlet header 29 discharges through pipe 32 at the end opposite the inlet end of header 28. f

In the type of boiler shown, the boiler proper is ordinarily suspended from above through the medium of a steel framework, and in the form illustrated I have shown the boiler suspended from the transverse beams 33 by means of a number of straps or slings 34 passing around the drums 1, 2, 8 and 9. Drums 17 and 18 may be mounted as shown upon saddles 35. The superheater headers 28 and 29 are carried by slings or straps 36, while the intermediate header 27 is mounted in saddles 37 on the beams 33. The saddles 37 are preferably of any known form of resilient or spring type and drums 17 and 18 may also, if desired, be spring suspended although spring suspension of these drums is not essential.

It will be obvious 'to those skilled in the art that the specific manner of supporting theseveral drums and headers is subject to wide variation, but it is to be noted that the steam and water drums of the boiler are fixedly supported with respect to the position of the superheater headers so that the relative position of these drums with respect to the headers remains unchanged. rlhis is important as it prevents displacement of the superheater elements 30 with respect to the boiler under the influence of expansion or contraction, and therefore eliminates difllculties due to leakage at the points where the superheater elements pass through the portion of the boiler setting indicated at 38. This relatively fixed position as between the boiler drums and the superheater headers is made possible by the flexibility of the connections between the steam and water drums of the generating units and the superheate'r headers. Instead of the usual rigid piping connection from steam nozzles on the boiler drums to the superheater inlet header, I have substituted a flexible tubular structure by means of which the steam off-take drums of the generating units are connected to an intermediate header and the only rigid connection is the relatively short pipe 31 connecting this intermediate header with the superheater inlet header. l/Vith the super'- heater inlet header in fixed position, expansion and contraction in the short pipe 31 is taken care of by the slight movement of the intermediate header 27, such movement being permissible because of the relatively flexible connection between this header and drums 17 and 18 provided by tubes 25 and 26.

The relatively flexible tubes 19 and 2O also absorb the expansion .stresses so that drum 17 may be mounted in a relatively fixed position with respect to drum 1 and drum 18 in a relatively iiXed position with respect to drum 9. In some extreme cases it may be desirable to mount drums 17 and 18 on spring saddles or their equivalent, in order to provide freely flexible units connecting drums 1 and 9 with the intermediate header 27.

A further and very important advantage which is derived from the use of my invention lies in the improved distribution of steam flow from the boiler drums to the superheater which the construction illustrated secures. Because of the large number of tubes 19 and 2O which may be employed between the steam and water drums and the steam drums, the velocity of the steam leaving the steam and water drums may be reduced to a rate below the critical velocity at which it is practically impossible to separate entrained moisture. This velocity is in the neighborhood of 100 feet per second. Furthermore, the distribution of these tubes along the entire length of the steam drum assures even flow of the steam from the drums as contrasted with the uneven How taking place when steam is taken from the steam and water drum through one or more nozzles delivering to large steam pipes.

Drums 17 and'18 serve to separate what little moisture may be carried over from drums 1 and 9, and the distribution of steam low from these drums is also relatively uniform along the length of the drums because of the arrangement of tubes 25 and 26. There will be a certain tendency to disturb the evenness of flow from these drums due to the pressure drop thrugh the intermediate header 27'but steam flow through the connecting tubes 25 and 26 will be maintained at a relatively Vvuniform rate due to the fact that the increased velocity through some of the tubes 25 and 21S-which would be the result of unequal distribution would cause an increase in the resistance to flow through the tubes carryingthe greatest amount of steam, and this increase in resistance in some of the tubes marras? would tend to, establish ank equilibrium of flow in which the steam distribution is substantially. uniform. y

The arrangement described` 'further permits the advantageous .arrangement oi crossflow` through. the superheater,thatv is, the placing-oit the inlet end discharge connec-v` tions to the'superheaterfat opposite ends y thereof to insure the most luniform distribu-- tion of steam through the superheater ele-V ments.

It will be noted that a balancing connection between the steam 'and wat r drums o'i the two generating units is provided through the flexible connection formed by header 27, drums 17 and 18 and tube rows 19, 2G, 25 and 26. This connection is oil relatively large area so that a quick balancinl of pressures between the two generating unitsV may be secured. Thisis highly important in boilers of this type, particularly where the combustiony gases leave through separate lues, as any change in the flue gas regulation which causes an unequal flow, even though it is onlymomentary, of gases over the two units causes the difierential pressure within the boiler units which must be immediately equalized if a dangerous drop or rise in the water levels of the two units is to be avoid.

Heretofore it has been common prac to c onnectdruins 2 and 8 in this type of bonV by water circulators similar to circu'at and 13. The circulation between d 3 and 8 is, however, normaliy very sluggis and the circulators connecting the dr c moreover exposed to verv intense heat. combination of circumstances frequently results in serious trouble with these circulators, due to overheating through lack oit' circulation or because of sludgeA accumulations which the circulation between these two drums is insuflicient -to carry away. 'lilith the novel arrangement of my inventien, these circulators may be omitted as shown in Fig. 1, as pressure equalization between the drums is sutiiciently rapid through the steam space provided to quickly equalize pressure between the two units. 1f an additional equalizing path is desired, tubes may be provided directly connecting the steam spaces of 2 and 8, but because of the path provided between these drums by way of drums 1'? and 18 and header 27, the number of tubes directly connecting drums 2 and 8 may be greatly re'- duced, or, as I have shown, entirely omi ted.

A still further advantage of my invention resides in the decreased cost of constructing the boiler due to the elimination of steam. nozzles and steam piping. in high pressure boilers' the cost of constructing drums with large nozzles secured thereto for steam otitake purposes is excessive asis also the cost of high pressure steam piping lt will be observed that if constructed inl accordance with my invention, no nozzles Whatever are required and the Steam! piping is.. reduced; te'. a minimum which, moreover, is of the least expensive form comprising short straight. lengths and elbows.

.Coming now toFig. 3, the invention is shown in al slightly modified form applied. to a.k bciler coniprisingtwin generating units A and B. The unit comprises a singlesteam and water drum 1 connected by means ofbanlrs of generating tubes 3, li and 5,V to a mud drum 39, while thesimilar unit B comprisesthe steam4 and water druml9,con nected by tube banks g', 11 and112 to the mud drum 40. Themud drums 3,9 and lO-areconnected through the usual water screen tubes i1 lining thefurnace and' combustion chamber Suitable baiiiing directs the combustion gases over the generatingl units as indicated by the arrows to the separate breechings shown. Drums 1,. and 9 are connected respectively by the rows of tubes 19 and 20 to a single steam drum 42A which serves the same purpose as the drumsl and 18 shown in Fig. 1. Drum 4 2 maybe proT vided with baiiies 21 and 22 and suitable wa.- ter returnA pipes.l Tubesv25 and 26 connect. drum Llf2 with intermediate header 27 whichy is connected in the manner shown in. Fig.- 2 to the superheater inlet header 28. The su.-Y perheater arrangement isthe saine `as shown in 2. The superheater headerslare in this form also supported from the usual framework in relatively fixed relation with respect to drums 1 and 9".

It will also be obvious thatthe several ad;

vantages secured by the construction sllwnk in Figs. 1 and 2 will also. be inherent in. the

signed to operate at'relatively` lower ratingsr ln this form the steam and water drumsl and9 are connected directly to the intermediate header 27 by means of the` rows of tubes 413. and da 'which serve toabsorbl all of the expansion strains, It will beobserved that in this form of Construction the same advantages relativev to steam distribution and.` balancing of pressures between ythe generatev ing units and other advantages previously:

steam Vgenerating units each having a steam and water drum,a superheatervhaving an inlet header, anLintermediate-header con..-

nected to the inlet header, means located above the level of the steam and water drums and forming a steam separating space, a plurality of relatively flexible tubes connecting the steam space ot each ot said drums and said means, and a plurality of relatively flexible tubes connecting said means and said intermediate header, there being a greater y number of tubes between said drums and said means than between said means and said intermediate header.

2. A superheater boiler comprising` twin steam generating units of the semi-vertical type, each of said units having a steam and water drum and a steam drum, a plurality ot rows of relatively small tubes connecting each of said steam and water drums with its respective steam drum, a superheater having an inlet header, an intermediate header, a pluiality of rows ot relatively small tubes connecting each of said steam drums with said intermediate header, and a pipe connecting the intermediate header with the superheater inlet header.

3. A superheater boiler comprising twin steam generating units oi" the semi-vertical type, each of said units having a steam and water drum and a steam drum, a superheater having an inlet header relatively fixed with respect to said steam and water drums, an intermediate header, a pipe forming a rigid connection between the intermediate header and the inlet header, and a plurality oi relatively Aflexible tubes connecting the intermediate header with the steam space oi each of said steam drums and a plurality of substantially flexible tubes connecting each oit said steam drums with said steam and water drums.

4r. A superheater boiler comprising twin steam generating units ot the semi-vertical type, each of said units having a steam and water drum, a steam drum located above said steam and water drums and connected thereto, a superheater common to said units and having an inlet header relatively fixed with respectto said steam and Water drums, an

intermediate header of substantially the same size as said inlet header,a pipe forming a rigid connection betweenV the intermediate and the inlet headers, and a plurality ot relasaid tively `flexible tubes connecting the intermediate header with said steam drum.

5. A superlieater boiler comprising a pair of steam generating units each having a steam and water drum, a superheater having inlet and outlet headers one above the other, relatively iixed with respect to said drums and having two groups of elements, one for each of said units, connected to said headers in parallel, an intermediate header oi' substantially the same size as said inlet header and arrangedvin the same vertical plane as said inlet and outlet headers, means connecting intermediate -header to said inlet header, and a iexible connection extending the entire distance between each of said steam and water drums and said intermediate header and including tubes oi small section relatively to said headers.

6. A superheater boiler comprising a pair of steam generating units each having a` steam and water drum, a roof section intermediate said drums, a superheater having inlet and outlet headers arranged one immediately above the other and relatively fixed with respect to said drums and having two groups of elements, one for each of: said units, connected to said headers in parallel, said elements each having vertical portions extending through said root section, an intermediate header of substantially the same size of said inlet header, and arranged in same vertical plane as said head-ers, a connection between said inlet and intermediate headers, and a iexible connection extending the entire distance between said steam and water drums in said inlet header and including a plurality or" conduits of small size relatively to said headers.

7, A superheater boiler comprising a pair oi' steam generator units each having a steam and water drum, a siiperheater having inlet and outlet headers and having two groups of elements, one i'or each oit said units, connected to said headers in parallel, an intermediate header, said inlet, outlet and intermediate headers arranged in the same vertical plane and'niidway between said steam and water drums, means connecting said intermediate header to said inlet header, and a flexible connection extending the entire distance between each of said steam and water drums and said intermediate header and including tubes of small section relative to said headers.

l/VILBUR H. ARMACOST. 

